Gabion Retaining Walls for the Bonville Fauna Overpass on the Pacific Highway, New South Wales

As part of the 9.6 km Pacific Highway upgrade through Bongil National Park, a substantial fauna overpass was required at the southern end of the project to allow wildlife to cross the highway safely. The crossing had to accommodate both the northbound and southbound carriageways while creating enough retained earth above and around the highway to form the overpass.

The structure comprised separate precast concrete arch tunnels supported on cast in situ concrete base walls. To build the crossing above them, retaining walls up to 13 m high were required along the sides and over the tunnels, making the retaining system a critical part of the overall design. Maccaferri hexagonally woven mesh was specified for the wall facing.

To address these requirements, Abigroup Contractors approached Maccaferri for a design suggestion for a mass gravity gabion wall. Preliminary assessment was carried out using Maccaferri’s GAWACWIN mass gravity gabion design software, with the final design completed by SMEC Australia. Maccaferri also provided technical support on gabion design methodology and long-term durability.

Durability was a key consideration, with the client requiring a 100-year design life. In response, Abigroup used Maccaferri Galmac and polymer-coated gabion units, incorporating a 95% zinc and 5% aluminium alloy coating together with a polymer coating.

The installation was carried out by a specialist gabion contractor using temporary formwork and preformed bracing wires to help achieve the required wall finish. Maccaferri pneumatic closing tools with stainless steel rings were also used on site to support faster installation while maintaining the integrity of the gabion system

Completed in 2008, the retaining walls enabled the earth structure needed to form the fauna crossing over the highway. The project brought together transport infrastructure and environmental requirements in a single solution, using mass gravity gabion walls to provide the necessary retaining function while supporting the creation of a dedicated wildlife crossing through Bongil National Park.

The Bonville fauna overpass remains a strong example of how gabion retaining systems can be integrated into major infrastructure projects where significant retaining heights, long-term durability and environmental considerations need to be addressed together.

For more information about Maccaferri gabion and retaining wall solutions, contact us at info.au@maccaferri.com.